Resettable overload switch device for use in an electrical inductive apparatus



Nov. 7, 1967 c. E. LINKOUS I RESETTABLE OVERLQAD SWITCH DEVI CE FOR USE IN AN ELECTRICAL INDUCTIVE APPARATUS 2, 1964 4 Shee ts-Shee t 11 Original Filed Jan.

s m u WM 8 W i m m 5 mm a a C Y 4 3 7 B 2 .4 z 2 Q.

A u M -l .4 a ,I w 1 llilill a 4 a III:

Nov. 7,1967

' c. E. LINKOUS 3,351,790 RESETTABLB OVERLOM) SWITCH DEVICE FOR USE IN AN ELECTRICAL INDUCTIVE APPARATUS Original Filed Jan. 2, 1964 4 Sheets-Sheet 2 INVENTOR. ("law's l/hlfous,

ZWM

Nov. 7,1967 c E. LINKOUS 3,351,790

RESETTABLE OVERLOAD SWITCH DEVICE FOR USE IN AN ELECTRICAL iNDUUTIVE APPARATUS Original Filed Jan. 2, 1964 4 Sheets-Sheet 5 9a M s2 5/ y 99. A

, INVENTOR V Cla /s fiL/h/fnds,

y Attorney.

C. E. LINKOUS RESETTABLE OVERLOAD SWITCH DEVICE FOR USE AN ELECTRICAL INDUCTIVE APPARATUS 1964 Nov. 7, 1967,

v 4 Sheets-Sheet 4 Original Filed Jan. '2

1& f b

1\- I I (lay/Is ALMA 0a WQWM l/IIII/WA Mn su i I I I I i I Q I l 3,351,790" r RESETTABLE OVERLOADI SWITCHz-DEVICE FOR cover plate may be employedover the above components USE IN AN ELECTRICAL INDUCTIVE APPA- RATUS a I i Clovis E. Linkous, Fort- Wayne, Ind., assignor to General Electric Company, 'a corporation of New York Original application Jan. 2, 1964, Ser. No. 335,243, now

Patent No. 3,311,764, dated Mar. 28,1967. Divided I and thisv application Nov. 21, 1966, Ser; No. 595,870 Claims. (Cl. 310-68) ABSTRACT OF THE DISCLOSURE Thisinvention relates to resettable overload switch 7 devices and more particularly to an improved manually resettablethermal overload switchdevice of'the type suitable for use in the control of awinding circuit of electrical inductive apparatus,v such as dynamo'electric machines. The, device, when used in connection with dynamoelectric machines, maybe conveniently mounted within the machine frame as part of a winding control unit which is accessible from the frame exterior to to prevent entry of dust or their foreign material.

When the contacts are. opened, the spring turns the post in a direction such that the wedge enters'between the contacts and engages a support wall which together with the spring,,maintains it in that position. The post has the endremote from the end with the spring terminating in a handle section which projects beyond the support, away from the overload chamber, in a location accessible to the exterior of V contacts and wedge'may be returned to their original ponents which are capable of being efliciently' reset when- I ever, conditions justify.

go become more apparent permit, among other things, resetting of thedevice when such is desired.

The present applicationis a division of patent application S.N. 335,243, filed Jan. 2, .1964, now Patent 3,311,- 764 issued Mar. 28, 1967. v

It is a primary object of the present invention to provide an improved resettable overload device for use in electrical inductive apparatus, and it is a more'spcciiie object to provide such device of the type adaptable for use in the winding circuit of dynamoelectric machines.

It is another object of the present invention to provide an improved yet low cost thermal overload device which permits a reduction'in the number of connections and parts normally required and results in a low cost u i r It isafurther object of the present invention to provide a low cost manually resettable device for, use in a winding circuit which is readily assembled together, is efiicient in preventing energization of the winding circuit when conditions so dictate, and is capable of being easily reset when desired.

In carrying out the present invention inone form, I

provideanimproved manually resettable thermal overload device for use in an electrical inductiveapparat-us, such as for example in the winding circuitpfadynamoelectric. machine. The

mounted within anoverload chamber of a'isupport, the

7 contacts being connected in the'winding'circuit of the machine and'being responsive to a preselected adverse temperature condition within the machineframe. In the illustrated embodiment, these contacts are in a, normally closed position so that a closed electrical path is I furnished throughthe contacts under normal operating conditions within the frame. When the preselected condevice includes a pair of contacts 50 positions by merely turning the handle section 'of the insulator.

This arrangement is not only inexpensive to produce and easily installed but also furnishes a highly effective overload device with relatively few number of com- These and other advantages will from the following discussion. ,The subject matter whichI is particularly pointed out and distinctly'clairned in the concluding portion of this specification. My invention, itself, howevenboth as to its organization and method of operation, together'with further objects and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying drawing.

,t ric machine end illustrated in In the drawingf j FIG. 1 is a fragmentary plan elevational view, partly broken away, showing one end of a dynamoelectric machine incorporating the preferred embodiment of the present invention; A

FIG. 2 is a fragmentary side elevational view, partially broken away and insection of the same dynamoelec- 'FIG. 1" to show further 7 details of the winding control unit seen in FIG. 1;

' FIG. 3 is a fragmentary end view, partly brokenaway, of the machineend of FIG. 1 to revealdetails of the'terminal section of the control unit; 3

FIG. 4 is a schematic representation of the Winding control circuit for thedynamoelectric machine of FIG. 1; i FIG. 5 is a partial and enlarged view taken along line 55 in FIG. 1 to show further details of-the control unit and its mounting withinvthe motor frame} I FIG. 6 is an enlarged; fragmentary view in perspective of the-manner in which one side of the'control unit is mounted to, the machine frame;

T Q .FIG; 7 is a fragmentary view,- partially broken away,

showing thethermaloverload switch and manual reset components of- FIG.

6, with'the switch contactsj'being held in open circuit'by'the reset element'to're'veal the preferred form of the manually resettable overload de- 7 vice;

dition is reached, the contacts are caused to become sep- 7 and one and of the post furnishes the bias If desired, a-

FIG. 8 is a view taken along line 8-8 in FIG. 6 to show further details of the overload switch and manual reset components of the device; I i

i FIG. 9 is a view in perspective of the manual reset element seen in FIG. 8; i a

FIG. 10 is an enlarged partially exploded view in perspective of the control support and one type of relay switch which may be satisfactorily employed in the control support of the present invention; FIG. 11 is a view of therelay armature assembly taken along line 1111 in FIG. 10; and I I 7 FIG. 12 is a view in perspective of the movable armature relay switch assembly shown in FIG. 10. 1

Turning now to the drawings in more detail and in particular to FIGS; 1, 2, and 4, the preferred embodiment has been shown in connection with a dynamoelectrio machine and more specifically a single phase induc- 3,351,190 Patented Nov.7, 1967 the machine frame. Once the conditions within the frame return to normal, the

regard as my invention tion electric motor of the resistance split phase type. The motor includes a laminated stator core 21 of standard construction, formed by a stacked plurality of laminations punched from relatively thin magnetic contour. A distributed main or running winding 22 is arranged in stator winding accommodating slots in the usual way with winding end turns 23 projecting beyond each side face 24 of the core. For reasons of simplicity of illustration and brevity of description, only one side of motor 20 has been shown in FIGS. 1 and 2. An auxiliary or star-t wind ing 26 is displaced 90 electrical degrees from the main winding in the slots for the usual reasons. Each winding is wound with a number of turns of insulated wire; e.g., magnet wire, to form winding poles in the well-known manner, the windings being isulated from the core by standard slot lines 27. Both windings are adapted to be energized during starting conditions, while only the main winding is excited for running operation as will be explained more fully hereinafter.

The stator core is mounted within a cylindrical central shell 31, fabricated of sheet material like steel, of a motor frame, as by welding the stator to the shell at angularly spaced apart locations. Shell. 31 extends axially beyond winding end turns 25, terminating on each side in an edge 32 which is suitably connected to cast end shield 33 or an end frame. The connection shown in FIGS. 1 and 2 is of the rabbet type, with a number of angularly spaced apart through-bolts 34 securing the parts firmly together. Each end shield incorporates a central hub 35 mounting a bearing for rotatably supporting one end of a shaft 36, which in turn, carries a conventional rotor (not shown) having a cast squirrel cage type winding formed with end rings partially seen and indicated in FIGS. 1 and 2 by numeral 37.

The illustrated motor of the exemplification incorporates a single winding control support unit, generally identified by numeral 40, of the type disclosed and claimed in my co-pending application S.N. 335,243. As shown in FIG. 2, it has a single-piece electrically insulated casing or support 41, preferably molded of thermoresponsive material such as thermosetting epoxy resin and integral, yet electrically separated, generally formed into the shape of an L" to provide three interrelated supporting sections, a start winding switch accommodating section 43, an overload switch mounting section 44 and a terminal supporting section 45. As will be more clearly developed hereinafter, the interrelationship of these sections to one another as well as to other motor components achieves, among other beneficial results, a reduction in the number of electrical connections required, protection for the switch components, and versatility in use.

The start winding switch accommodating section 43 which is formed by one of the legs of the support, will be considered in connection with FIGS. 2 and 10. This section of generally block-like construction has an outer arcuate surface 51 complementary in configuration to the inner surface of motor shell 31. The free end 52 of the section is generally flat or planar for abutment against stator end face 24, intermediate the shell and winding end turns 24. A chamber or switch accommodating cavity is provided at surface 51, remote from winding end turns 24, the chamber being defined by bottom wall 54, inner and outer walls 55, 56 (as viewed from the motor stator) and side walls 57, 58. This chamber is especially suitable for supporting the switch relay components of the switch relays disclosed and claimed in my U.S. Patents 3,256,- 402 and 3,256,403. The switch relay disclosed in Patent 3,256,403 is shown in the drawings by way of example only and a more complete description of the relay details and operation are set forth in that patent.

FIGS. 1, 10, 11, and 12 reveal switch relay details of the exemplification. Briefly described, a pair of switch contact blades 61 and 62 are supported by enlargements 63 and 64 respectively, which are integrally joined to chamber wall 56 by a stepped construction through opening 66 indicated by number 65. Blade 61 is the movable blade having its blade extension 67 rigidly attached to enlargement 63 by a pair of rivets 68. In a like manner, the stationary contact blade is riveted to enlargement 64 such that blades 61 and 62 extend toward one another for cooperation. Movable blade 61 has a snap action and bracketed arrangement cooperatively connected to a relay anmature '71 by opposed brackets 72 and 73. This armature is connected above a core 75 mounted with its yoke section disposed adjacent wall 55 by a rivet 76 projecting through the yoke section and into the wall 54 of the chamber. The core accommodates an energizing coil 78 suitably attached by crimped connectors 79 to the terminations of a sensing coil 81 (FIG. 4) carried by the stator in the axis of the start winding. A recess 83 is formed in the section outwardly of walls 57 and 58 with channels 84 communicating between the recess and the chamber for passage of the relay coil wire extremities to the connectors. In addition, wall 55 has slots 85 connecting an opening 86 formed in wall 54 to permit motor winding extremities to permit the assembly of the end sensing coil to the relay coil and to locate the sensing coil wire extremities away from the stator for reasons of protection. Slots 85 allow this assembly while openings 86 provide the protection when the unit is in place. Wall 55 also furnishes the support for an impact mechanism 88, which has a shaft 89 situated in bearing hole 91.

Support 41 is mounted in the motor and carried by shell 31 in the manner shown by FIG. 2 with surface 52 abutting against the side face 24 of the stator core, adjacent the inner surface of shell 31. The illustrated means for achieving this mounting is shown in FIGS. 5 and 6. A pair of spaced apart and opposed, generally Z-shaped, elongated brackets 93 are attached to the inner surface of the shell at one end 94 by welding or the like and extend axially away from the stator. The brackets have recesses next to shell 31 which, along with the inner surface of shell 31, provide opposed narrow channels 99 for accommodating a curved sheet of electrdical insulation 8 such as fiberboard conforming in contour to the shell. The brackets are bent just below the recesses to furnish opposed flanges at their free ends for fitting beneath complementary shoulders 96 made integral with support section 43 and extending laterally away from that section. The flanges serve to hold support 41 firmly against insulation 98 which is sandwiched between shell 31 and support 41 and covers the start winding switch chamber in section 43 thereby shielding it, both electrically and physically. Support unit 41 is easily installed before the end frame 33 is attached to shell 31 merely by sliding insulator 98 into the bracket channels near the shell and then pushing the support shoulders 96 along the opposed bracket flanges until surface 52 rests against the stator. When end frame 33 is fastened to shell 31, the unit is held in the brackets, between the stator and the end frame and thus the aixal length of the motor beyond the stator is established by the length of support 41. It will be seen than in its assembled relation to the motor, the start winding switch is supported away from the winding end turns 23 (FIG. 2) is an enclosed compartment in which the switch contacts are protected from exposure to dirt and foreign matter and the switch is electrically isolated by support 41 and insulator 98.

Now referring to section 44, and to FIGS. 2, 5 7, and 8, an overload switch receiving chamber 101 opens toward the winding end turns on the other leg of support 41. This chamber is constructed, by way of example, to house an overload switch having switch components similar to those disclosed in Patent No. 2,771,528 issued to D. E. Moran on Nov. 20, 1956. A bimetal element 102 is provided having a susbtantially O-shaped configuration (FIG. 8) with an indentation 102a mounting a movable contact 103 on its underside. The indentation prestresses the bimetallic element 102 to provide the requisite snap action in response to temperature changes. A

conductive material such as steel, is provided over ele ment 102, with a portion-105receivedin support recessed seat 106 communicating with the'chamber; A point 108 of member 104 adjacent the edge-of'element 102 is secured to an indentation in mountingmernber as'by spot Welding.

A terminal portion for movable contact'103 is formed on the extreme end 'portion 109, of member 104 which extends beyond recess 106 and is riveted to outer surface 110 of support section 44 which faces-the motor end turns 23in the assembled position of unit 40. Hollow, electrically conductive -rivet 109a '(FIG; attaches portion 109 firmly to surface-110a. Mounting member 104 has an opening in the center thereof and a threadedhole 111 (FIG. 8 is furnished through the bottom wall 112 of the chamber, extending to support section 44. A suitable screw 114 is seated over the opening inimember 104, projects down through it and into threadjhole lllfor mounting that end of member '104'.

" The stationary contact121 with'which contact 103 cooperates," is mounted on one leg portionof an L-shaped member 122' which projects through-an 'openingformed in the'bottom wall 112 -ofthe" overload chamber. The other leg portion is locked in place by'anumberof ears 123 bent over after member 122 has been inserted into the opening. The terminal for thest'ationary contact, un-

of the motor, the spring 142 turns insulator 132 from the original biased or extended position shown in FIG.

5 to that of- FIGS. 7 and 8 where wedge 144 becomes disposed between the separated contacts to maintain them-in the open circuited position. A wall of the chamber stops the wedge and retains it between the contacts. As will be seen from FIG. 4, this disrupts the circuit to the'start and'main windings tostop the operation of the motor. Once the circumstance causing the adverse temperature condition has been corrected, the switch contacts may be closed. merely by manually rotating the insulator to the extended position shown in FIG; 5, outwardly of contacts 103, 121, and the contacts will snap closed. V I

An electrical insulator cover plate 147, best seen in FIG. 5 is employed to cover the communicating overload ,and insulator cavitiespwith an aperture 148 permitting the extreme end of the insulator to pass through the like that shown in the aforesaid patent, 'is a generally Z-shaped conductor'stripor link of metal 124 shown in FIG. 5 which has one portion 125 projecting into" the chamber and through an opening 127, in the bottom to form an external male terminal .post 128(*FIG. 2) upstanding from terminal section 44; .Here a'gain, suitable ears on the terminal member may be bent over beyond opening 127 after assembly to lock the part in place. The other end 131 of strip 124 is connected to blade extension 67 of the movable contact for the switch relay. Stationary contact 121'is electrically connected to link 124 within the chamber through a suitable serpentine .heater129, joined at each end by brazing or the like cover. Suitably provided studs 1149, made integral with section 44 and projecting outward from its upper sur- 7 face, form the'm'eansl 'to' hold the cover firmly over the cavities. This cover is installed after the overload switch components and insulator 132 have been assembled in place. It therefore prevents dirt or other foreign matter from entering. the cavities and holds the respective ends of spring 142 in slot 141 and groove 143; v T1 In the illustrated embodiment of supportunit 40, certain terminals which control the winding circuit are conventionally located Where theyare, most accessible for easy winding. In addition the aforedescribed locations of the switch relay and overload switch permits the-use of common terminal to make safe connections. More specifically, terminal section 45, formed on thelsarne de- -pendin'g leg as'the overload supporting section 44, but

to contact 121 and link portion 125 respectively. This heater is in heat transferrelation with bimetallic element 102. The thermaloverload switch device is'responsive to excessive current as well as to excessive ambient temperature and will open with a snap action when a preselected adverse temperature condition has been reached by the motor. j

In the preferred embodiment of the overload switch device and by an important feature of the present invention, the device is manually resettable by an improved arrangement. Support 41 mountsa rotatable, spring loaded single piece electrical insulator 132, shown in FIGS.

remote from the'interior of the motor, is exposed'to the exterior of the machine. A flanged opening 152 furnished in end frame 33 permits access toterminal section'45 as well as to the handle of insulator 132 for resetting the overload device. A'suitable removable cover or plate 154 may be utilized toenclose theopening, screws 156 being used to mount'the cover over the opening. I

Power leads 161, .162 which enter the'inotor through conduct opening 166 in end frame 33 (FIG. 3) are seated in recesses 173 and 174 formed in section 45 The'manual power control switch for the motor is indicated by numeral 175 in line 161 as seen in FIG. 4. These line terminals are each providedin the form of an L with the terminals upstanding from the'spaced apart recesses to provide an electrical barrier therebetween. Terminal leg 163a of terminal 163 is secured to the support by hollow electrically conducting. rivet 109awhich, as previously mentioned, also holds portion 109 of the overload switch 5, 7, 8, and 9, which may made of any suitably hard insulating material such as molded thermo-setting plastic. It includes a cylindrical stepped post accommodated in a complementary hole 134,. extendinginto aichamber' or 7 cavity 135 which opensinto the overload chamber in the vicinity of contacts 103, 121; The postterminates at one end beyond terminal section .44 in a serrated handle section 136 for manual operation and carries an integral radial enlargement 137 seated on shoulder 138 of cavity 135. The insulator is heldlin place by a nut 136a engaging the outer surface of section 45. A transverse slot 141 formed in the extreme end of the insulator remote from section 136 receives one end of a coil spring 142 with the other end being held in grooves 143 nearshoulder 138 to provide the requisite compressive support for the arrangement. The spring has several convolutionswrapped around the insulator post under compression for this purpose. A lateral projection or wedge 144 made integral with, but beneath, enlargement 137, is adapted to be held tion (FIG. 5) by spring 142. 7

Upon opening or separation of the contacts, as will occur under adverse. temperature operating conditions or biased against'contacts 103, 121, in their closed posimounting member. The other line terminal 164 similarly has itsleg 164a attached in place by a hollow electrically conductin-g rivet 167 extending through the support ma-{ terial. Hollow rivets are preferred since screws-184- and 185 may -be received in them for making an alternate 'type connection with line 161," 162. A generally Z-shaped terminal strip 170 is held by rivet'167 on the side of support 41, remote from section 45 such that one of its ends 171, formed into-a male quick connect terminal, is

located next to relay switch terminal 168 for convenience ofmaking the connections to the start winding. The other endof strip 170 enters an opening communicating with section, 45 and provides an upstanding. male quick :connect terminal 172 disposed near terminal 128. Consequently, these two terminals can bereadily utilized for connecting main winding 22 to the power lines, the manual control for the motor. If reverse rotation of'themotor is desired, the necessary change of connections canibe made easily by reversing or interchanging the main Winding connections at terminals 128, 172.

From FIGS. 3 and 4 and the foregoing discussion, it will be appreciated that in support unit 40, the line lead connections, main winding lead connections, and overload switch insulator handle are all easily accessible from end frame opening 152. In addition, the start winding terminals 168 and 171 have a common and unobstructed location, facilitating their connection with the start winding. Moreover, calibrating screws 177 for adjusting the net force on armature of switch relay may also conveniently extend from terminal section 45, through the support 41 and into the chamber accommodating the re-- lay in the other leg of support 41. The heads of these screws can be reached at a location common to the one and main winding terminals without difiiculty.

The manner in which the unit mounts the start winding switch and overload switch also permits simple and common interconnections between the components of the start and main winding circuits and allows versatility in use. As to the interconnection benefits for example, short electrical conducting strip or link 124 makes a common connection for a side of the start winding, the overload switch (contact 121), and the start winding switch (blade 61).

While in accordance with the patent statutes, I have described what at present is considered to be the preferred embodiment of my invention, it will be obvious to those skilled in the art that numerous changes and modifications may be made therein without departing from the invention and it is therefore aimed in the appended claims to cover all such equivalent variations as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. For use in a single winding control unit of a dynamoelectric machine having a support, the arrangement including an overload switch carried by the support comprising a pair of normally closed contacts, and an insulator post turnably mounted by the support adjacent said contacts, said post including an electrically insulated wedge having an original position outwardly of the contacts, spring means connected to said post biasing said wedge against said contacts in the original position when said contacts are closed, said contacts having means responsive to the operation of the machine to open them, said spring means turning said wedge between the contacts when the contacts are opened, means retaining said wedge between said contacts, and rotatable means for returning said wedge to its original position.

2. A resettable overload device'for use in an electrical inductive apparatus comprising a support formed with a chamber; the device comprising a pair of switch contact elements disposed in said chamber having closed and open positions; an insulator post turnably mounted by said support adjacent said contact elements and having a lateral projection rotatable between first and second positions, with one of the positions being located between said contact element at the open position; spring means attached between said insulator post and support for biasing said insulator post toward said second position; said support having means for stopping said projection in said second position; and a section connected to said post for turning said post to return said lateral projection to said first position.

3. The overload device of claim 2 in which said support has a cavity in communication With said chamber and a shoulder receiving a part of said post, and said post has a radial enlargement formed next to said lateral projection seated on said shoulder for support and proper location of said post.

4. The overload device of claim 2 in which one end of said post is formed with a transverse slot for receiving one end of said spring means and the other end of said post terminates in said section which projects beyond said support on the side thereof remote from said chamber to be accessible for turning said post to return the lateral projection to its first position.

5. The overload device of claim 4 in which electrical conducting means is attached to one of said contact elements and projects through said support, said electrical conducting means being accessible on the same side of said support as said section of the post.

References Cited UNITED STATES PATENTS 2,271,813 2/1942 Clayton 200 -153 2,473,485 6/ 1949 Vickers 310-68 2,567,361 9/1951 Bean 2001 16 2,682,005 6/1954 Hemphill et al. 310--68 3,209,104 9/1965 Malone 200-l22 MILTON O. HIRSHFIELD, Primary Examiner.

J. D. MILLER, Assistant Examiner. 

1. FOR USE IN A SINGLE WINDING CONTROL UNIT OF A DYNAMOELECTRIC MACHINE HAVING A SUPPORT, THE ARRANGEMENT INCLUDING AN OVERLOAD SWITCH CARRIED BY THE SUPPORT COMPRISING A PAIR OF NORMALLY CLOSED CONTACTS, AND AN INSULATOR POST TURNABLY MOUNTED BY THE SUPPORT ADJACENT SAID CONTACTS, SAID POST INCLUDING AN ELECTRICALLY INSULATED WEDGE HAVING AN ORIGINAL POSITION OUTWARDLY OF THE CONTACTS, SPRING MEANS CONNECTED TO SAID POST BIASING SAID WEDGE AGAINST SAID CONTACTS IN THE ORIGINAL POSITION WHEN SAID CONTACTS ARE CLOSED, SAID CONTACTS HAVING MEANS RESPONSIVE TO THE OPERATION OF THE MACHINE TO OPEN THEM, SAID SPRING MEANS TURNING SAID WEDGE BETWEEN THE CONTACTS WHEN THE CONTACTS ARE OPENED, MEANS RETAINING SAID WEDGE BETWEEN SAID CONTACTS, AND ROTATABLE MEANS FOR RETURNING SAID WEDGE TO ITS ORIGINAL POSITION. 